The progestin 17,20 alpha-hydroxypregn-4-ene-3-one (17,20 alpha-OHP) is being studied throughout pregnancy, labor and delivery in humans and in the baboon. The effect of the administration of synthetic glucocorticoid to pregnant women or baboons on the plasma levels of 17,20 alpha-OHP is also being studied. The levels of 17,20 alpha-OHP will also be measured in SGA, LG and women with toxemia of pregnancy. The plasma clearance and tissue distribution of human and rat transcortin has been studied in the rat and hamster. The mechanism of uptake and metabolism of asialotranscortin in isolated rat hepatocytes is being studied. These studies will be extended to a comparison of the effect of transcortin and asialotranscortin on the uptake, metabolism and distribution of cortisol and progesterone in isolated hepatocytes.